It’s an excel rim so it’s designed for motocross use, no worries about the bead.
If you’re on the fence between a xr or xc I would absolutely buy an xc. I have literally spent thousands on suspension, crash bars, skid plate, and wheels to basically make my bike a xc. The only reason I didn’t buy one in the first place is because I have a 30 inch inseam so seat height is an issue.
As far as wheel size goes between the 19” and 21” I don’t think it’s a big deal. I’ve had bikes with both sizes. Realistically if you own a tiger you will probably have a 50/50 knobby tire on it, so you’ll never be that hard into a corner to notice. Off-road difference is negligible in my opinion.